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Graft polymers and use thereof

a technology of graft polymer and etching process, which is applied in the field of patterned device manufacturing, can solve the problems of inability to achieve the selectivity of direction (anisotropy) considered necessary, and inability to achieve well-defined edges on etched surfaces

Inactive Publication Date: 2001-03-06
IBM CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The presence of the alcohol prevents crosslinking and facilitates handling of the graft polymer permitting it to be readily processed such as coated onto a substrate. However, upon removal of the alcohol such as by evaporating, the polymer will then form a cross-linked material. Accordingly, the presence of the alcohol provide a composition that can be thought of as being a latent crosslinkable composition.
Furthermore, the improvement in RIE retardation can be enhanced by providing the organometallic compounds with a silicon, tin and / or germanium. This can be accomplished by reacting the organometallic compound with a silicon, tin and / or germanium compound that has an active hydrogen to react through one of the alkoxy groups of the organometallic compound and leaving other alkoxy groups intact for subsequent grafting.

Problems solved by technology

These wet chemical processes suffer from the difficulty of achieving well-defined edges on the etched surfaces.
In other words, conventional chemical wet processes do not provide the selectivity of direction (anisotropy) considered necessary to achieve optimum dimensional consistent with current processing requirements.
Moreover, such wet etching processes are undesirable because of the environmental and safety concerns associated therewith.
However, a crucial challenge posed by the reactive ion etching relates to providing photoresist compositions that are sensitive to the radiation employed in its imaging procedure but resistant to the reactive ion etching.
A particularly harsh environment for the resist material involves those RIE processes using Cl / O plasma.
Most resist materials do not survive long enough in this environment to provide proper protection.
However, although the above discussed non-chemically amplified resists based upon the polymers disclosed in U.S. Ser. No. 08 / 700,348 and 08 / 717,644 perform quite well lithographically, their resistance to withstand plasma environments and especially Cl / O plasma is not satisfactory.
It has also been found that the available commercial e-beam resists offer little protection in this plasma environment.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

To a solution of about 1 g of poly(2-hydroxyethyl methacrylate) in about 15 ml NMP were added about 8 ml ethanol followed by a solution of 0.3 g of Tyzor TOT in 2 ml ethanol. The last solution was added dropwise with stirring. The solution was spin coated onto Si wafers at 2000 RPM. The wafer was baked at about 100.degree. C. for about five minutes. The final film thickness was 0.375 microns.

The film was exposed with e-beam at various radiation intensities and developed for 2 minutes in tetraethylammonium hydroxide (TMAH) 0.265%.

To illustrate the effectiveness of the present invention, Tyzor TOT is a commercially available alkoxy titanate. Its addition to the poly(2-hydroxyethyl methacrylate) reduced the etch rate (in a chlorine / oxygen plasma environment) from 2220 .ANG. / min for poly(2-hydroxyethyl methacrylate) to only 800 .ANG. / min. This compares favorably with the rate of Novolak (825 .ANG. / min), an industry standard.

The improved RIE resistance rate is evident from the data prese...

example 2

A mixture of tetraisopropyl titanate and 2-hydroxyethyl-1-trimethyl silane with a mole ratio of 1:4, was heated under nitrogen for one hour at 100.degree. C. and fractionated in vacuum to remove isopropanol. When no more isopropanol distilled, the product was distilled at 0.1 mm Hg. The product contained silicon at a ratio that indicated that one of the isopropanols was replaced with 2-hydroxyethyl-1-trimethyl silane. This product was used as titanate additive in place of Tyzer TOT according to example 1 above to improve RIE resistance and resist performance.

The resist graft polymized with the additive of this example has superior RIE resistance compared to resist graft polymerized with the Tyzor TOT additive according to example 1.

example 3

A mixture of tetraisopropyl titanate and octadecanol with a mole ratio of 1:4, was heated under nitrogen for one hour at 100.degree. C. and fractionated in vacuum to remove isopropanol. When no more isopropanol distilled, the product was distilled at 0.1 mm Hg. The product incorporated the octadecyl chain. The product was used in place of Tyzon TOT according to example 1.

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Abstract

Solutions of graft polymers of a polymer having reactive hydrogen groups and grafted through reactive hydrogen groups an alkoxy metallic compound wherein the metal is titanium, zirconium and / or hafnium are useful as photoresist materials which are resistant to plasma. Also, compounds and graft polymers wherein the alkoxy metallic compound also contains silicon, tin or germanium are provided.

Description

The present invention relates to certain solutions of graft polymers which can be used as photoresists and which exhibit enhanced resistance to plasma and especially to Cl / O plasma used in reactive ion etching. The present invention is concerned with the compositions as well as their use in lithography. For instance, the materials of the present invention are suitable for use in device fabrication on all optical, e-beam, x-ray and ion-beam lithography tools.The present invention is also concerned with certain graft polymers that exhibit increased hydrophobicity or increased hydrophilicity depending upon the characteristics of the moiety grafted onto the polymer. Moreover, graft polymers of the present invention can be grafted so as to create a permanent graft of a dye thereon.BACKGROUND OF INVENTIONIn the manufacture of patterned devices and especially microelectric devices, the processes of etching different layers which constitute the finished product are among the most crucial st...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): C08F8/00C08F8/42
CPCC08F8/42
Inventor AVIRAM, ARIBABICH, INNA V.
Owner IBM CORP
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